Free People Beach Green Cowl Neck Shirt

Free People Beach sage green, cowl neck, long sleeve top. I have absolutely no idea what size this shirt is. I bought it here and the previous seller didn’t know either. There are photos of both tags, neither says the size. Knowing me, it’s either a S or M. I’m 5’8” and weight about 120lbs and it fits me perfectly. If you would like any additional photos or measurements, I’m happy to do so. The last photo is of the cowl neck flat out. Armpit to armpit: 20” Front hemline under cowl neck to bottom hem: 22”, back is 24” Bottom hemline side to side: about 28”